text: Noddack and her husband-to-be looked for the then still unknown elements 43 and 75 at the Physikalisch-Technische Reichsanstalt. In 1925, they published a paper (Zwei neue Elemente der Mangangruppe, Chemischer Teil) and called the new elements rhenium (75) and masurium (43). They named the elements rhenium in respect of Idas birthplace, and masurium in honor of his. After scientists were sceptical of their results, the Noddacks began to perform more experiments to confirm their discoveries.  Only rheniums discovery was confirmed. They were unable to isolate element 43 and their results were not reproducible. These achievements led to Ida being awarded the German Chemical Societys prestigious Liebig Medal in 1931.
  Element 43 was definitively isolated in 1937 by Emilio Segrè and Carlo Perrier from a discarded piece of molybdenum foil from a cyclotron which had undergone beta decay. It was eventually named technetium due to its artificial source. No isotope of technetium has a half-life longer than 4.2 million years and was presumed to have disappeared on Earth as a naturally occurring element. In 1961  minute amounts of technetium in pitchblende produced from spontaneous U fission were discovered by  B. T. Kenna and Paul K. Kuroda.
  Based on this discovery,  Belgian physicist Pieter van Assche constructed an analysis of their data to show that the detection limit of Noddacks analytical method could have been 1000 times lower' than the 10 value reported in their paper, in order to show the Noddacks could have been the first to find measurable amounts of element 43, as the ores they had analyzed contained uranium.
  Using Van Assches  estimates of the Noddacks residue compositions, NIST scientist John T. Armstrong, simulated the original X-ray spectrum with a computer, and claimed that the results were "surprisingly close to their published spectrum!"
  Gunter Herrmann from the University of Mainz examined van Assches arguments, and concluded they were developed ad hoc', and forced to a predetermined result.
  According to Kenna and Kuroda technetium content expected in a typical pitchblende (50% uranium) is about 10  g/kg of ore.
  F. Habashi pointed out that uranium was never more than about 5% in Noddacks' columbite samples, and the amount of element 43 could not exceed 3 × 10  µg/kg of ore. Such a low quantity could not be weighed, nor give X-ray lines of element 43 clearly distinguishable from the background noise. The only way to detect its presence was to carry out radioactive measurements, a technique the Noddacks were not able to employ, but Segrè and Perrier did.
  Following on the van Assche and Armstrong claims, an investigation was made into the works of Masataka Ogawa who had made a prior claim to the Noddacks. In 1908 he claimed to have isolated element 43, calling it Nipponium. Using an original plate (not a simulation), Kenji Yoshihara determined Ogawa had not found the Period 5 Group 7 element 43 (eka-manganese), but had successfully separated Period 6 Group 7 element 75 (dvi-manganese) (rhenium), preceding the Noddacks by 17 years.
  However this claim has been disputed by chemistry historian Eric Scerri in his book titled "A Tale of Seven Elements"